The present disclosure relates to dual-ovenable food containers, i.e., containers that can be used both in a conventional oven and in a microwave oven for heating or cooking food contents.
Various types of food products are currently being packaged in containers that are specifically designed to be heated in either a conventional oven or a microwave oven. Some such dual-ovenable containers are formed entirely of polymer material(s). For example, dual-ovenable thermoformed plastic trays are used for some frozen food products that are to be heated or cooked while still in the tray. A membrane lid is sealed to the top surface of the container. Other dual-ovenable containers are formed from composite laminate materials typically including a paperboard layer with one or more polymer layers. In many cases, such dual-ovenable laminate containers are thermoformed or stamped.
While thermoforming or stamping of paper-based laminates is suitable for making some container configurations, it is not suitable for all configurations. Thermoforming or stamping works well when the container is relatively shallow in comparison with its length and width, but can be problematic if the container depth is too great. In the case of containers formed from a paper-based sheet, which is essentially inextensible, the greater the depth of the container for a given diameter, the more wrinkles will be formed in the wall of the container. Such wrinkles can interfere with good sealing between the top of the container body and the lid.